1. Field of the Invention
This invention relates to an automatic pressurized fluid actuated control system that is used external of and in conjunction with a pile hammer or the like. More particularly, it is concerned with a pile hammer control system having a series of pressure sensitive interconnected valves. The control system is connected by conduit to orifices in the pile hammer housing, and the orifices, conduit and valves are arranged so as to control the sequence that pressurized motive fluid is delivered to and exhausted from the pile hammer.
2. Description of the Prior Art
Pile hammers and the like are typically operated by introduction of a pressurized fluid, commonly steam or compressed air, into a chamber having a movable piston therein. When the pressurized fluid has raised the piston to a predetermined height within the chamber, the pressurized fluid is exhausted from the chamber, and the piston falls to deliver an impact to the pile or other object being driven. It is axiomatic that the proper operation of a pile hammer requires that pressurized fluid be delivered to and exhausted from the chamber in an operational sequence determined by the position of the hammer piston within the chamber. Conventional pile hammers control the operational sequence by use of a slide bar and trip mechanism that mechanically actuate the exhaust valve when the hammer piston has been fully extended within the hammer chamber. The slide bar and trip mechanism present several disadvantages in that the mechanical parts are typically bulky and heavy, are integral to the hammer and therefore subject to extreme jarring from the hammer impact, and do not allow for variations in the operating stroke length of the hammer. Although there are some pile hammer control systems in the art that eliminate the need for a slide bar trip mechanism (see U.S. Pat. No. 3,645,342 issued to George C. Wandell), there have heretofore been no control systems that can be located external of a pile hammer, that are fluid actuated rather than mechanically actuated, or that allow for an adjustment in the hammer stroke length.